yesterday had a rough idle when cold and misfires on 1,2,4,5,6 cylinders. I changed plugs and secondary tensioners last year and used NGK BKR5EIX-11. Pulled number 5 today and there was baked on oil at the insulator interface. Could this leakage cause misfiring?

 

Check out this link- PLUG STUDIO / NGK

 

thanks. I guess I'll swap in some coil packs I have and see what happens.

 

Steve, clear the codes and check the codes right after starting and continuously thereafter untii the first misfire code appears.

Under some fault conditions a single failed coil can cause multiple cylinder misfires, but it usually shows up as the first code registered on OBDII.

 

Steve, thanks. That is interesting. The misfire was so infrequent that it was days between occurrences. I changed out 2 of the 5 coils and will see what happens.